In certain drive shaft systems, it is desirable to have a single input shaft used to drive two output devices through a pair of drive shafts. For instance, applications arise where it is beneficial to drive two rotating accessories from a common gearbox pad. Such situations often arise in aircraft applications. A single input shaft, through a gearbox, might be used to rotate two output shafts independently coupled to a blower and the rotor of a generator.
In applications of the character described, it often is desirable and sometimes necessary to design the rotating shafts such that failure of one shaft does not affect the operation of the second shaft. This can be accomplished through a shear section in the one shaft.
Of course, in aircraft applications, space requirements are absolutely critical. This includes both axial as well as diametral space limitations. Shear sections or frangible elements of drive shaft systems are known, for instance, in U.S. Pat. No. 2,941,473 to Lorenz, dated June 21, 1960. In this patent, a single drive shaft operates a plurality of pumps located axially of the shaft. The pumps simply are arranged at axial locations and coupled to the shaft by frangible coupling members. Any number of pump units can be so driven simply by extending the length of the shaft. In such applications as aircraft applications, such liberal use of axial dimensions is not possible.
This invention is directed to a new and improved coaxial drive shaft structure with a shear section, using telescoped drive shafts to provide an efficient and compact device.